code: def upgrade():
      bind = op.get_bind()
      session = orm.Session(bind=bind)
      runs = session.query(SqlRun).all()
      for run in runs:
          if not run.user_id:
              continue
  
          tag_exists = False
          for tag in run.tags:
              if tag.key == MLFLOW_USER:
                  tag_exists = True
          if tag_exists:
              continue
  
          session.merge(
              SqlTag(
                  run_uuid=run.run_uuid,
                  key=MLFLOW_USER,
                  value=run.user_id,
              )
          )
      session.commit()
  
file_path: mlflow/mlflow/store/db_migrations/versions/90e64c465722_migrate_user_column_to_tags.py
imports: from alembic import op
  import sqlalchemy
  from sqlalchemy import orm, Column, Integer, String, ForeignKey, PrimaryKeyConstraint
  from sqlalchemy.orm import relationship, backref, declarative_base
  from mlflow.utils.mlflow_tags import MLFLOW_USER
label_desc: Use image node_id 1 for calling a global function with example usage: upgrade() without return types